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What is the effect on the graph of the function f(x)=x when f(x) is replaced with -f(x)+4

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. how many hours after the truck's departure will the two meet?

Write the equation in general quadratic form: plz !